This thriller at least keeps us gripped as it strands its characters in a hopeless situation. But it's so reminiscent of Open Water that it's hard to care what happens.

Six friends gather for a sailing holiday the coast of Mexico. Amy and James (Pratt and Speight) arrive with their baby daughter. Zach and Lauren (Lange and Hillis) are the singles flirting shamelessly. And their host Dan (Dane) has bimbo Michelle (Richardson) along for the ride. But when they all dive in for a swim, they neglect to lower the ladder. Now they can't get back on the boat--a problem compounded both by relational issues and the fact that there's a baby sleeping on the boat.

To their credit, the filmmakers make this premise fill the running time without stretching it out. There's a lot going on here, from their various attempts to get back on the boat to the interpersonal tensions that flare up for various reasons. The film mixes lacerating bitterness and suggestive humour in jarring ways that plunge us into the sea right alongside these people.

And director Horn keeps the camera right there--bobbing along, diving down, swirling above, never showing us more than the characters can see, cutting away to give glimpses of their inner hopes and fears. Shot in Malta, the film's wide-screen texture makes the most of the minimalist setting. You'd think that watching six people bob in the water alongside a drifting yacht would be static and dull, but we're hooked to the shifting story and moments of raw intensity.

The fresh-faced cast is superb, making the most of the sketchy characters. Each actor has moments that sharply highlight who they are and surprise us with unexpected actions. But the quick set-up and their panicky freak-out set us against them; they're just too angry or jealous or stupid. And since we've seen this kind of movie before, we accept the possibility that they're all doomed long before they do. Still, the film is jammed with sequences that work brilliantly on scales both small (memories and regrets) and large (actions and injuries). The result is horrific and harrowing, but not particularly emotional.